The present invention relates, generally, to the field of automatic implantable defibrillators. In such implantable defibrillators, the defibrillation pulse is stored and delivered by a high voltage capacitor; this capacitor is short circuited in order to terminate the defibrillation pulse.
A majority of defibrillators, found in the prior art, are short circuiting the charged capacitor which is a waste of energy. This energy could easily be applied to the fibrillating heart. Also, by short circuiting the charged capacitor, a significant amount of electrical stress is absorbed through the electronic parts of the defibrillator circuit. This electrical stress shortens the life of these parts.
One attempt to use the wasted energy of the capacitor is by using triphasic wave defibrillation. U.S. Pat. No. 4,637,397 to Jones et al discloses a defibrillator that uses a first conditioning pulse, followed by a second pulse of opposite polarity used for defibrillating, and finally a third pulse having the same polarization as the first pulse.
The following description discloses a biphasic pulse generator for an implantable defibrillator which uses only two pulses to deliver more energy stored in the charged capacitor to the fibrillating heart and thus, lowering defibrillation energy requirements.